Abstract:

A plurality of salient poles projecting toward a stator are arranged on a
rotor core along the circumferential direction while being spaced apart
from each other, and rotor windings are wound around these salient poles.
The rotor windings are short-circuited through diodes, respectively; and
when currents rectified by the diodes flow through the rotor windings,
the salient poles are magnetized to produce a magnet where the magnetic
pole is fixed. The width θ of each salient pole in the
circumferential direction is smaller than a width corresponding to an
electric angle of 180° of the rotor, and the rotor windings are
wound around each salient pole by short-pitch winding.

Claims:

1. A rotary electric machine including a stator and a rotor that are
disposed in spaced confronting relationship, whereinthe stator includes a
stator core on which a plurality of slots are formed and spaced apart
from each other in a circumferential direction around a rotor rotational
shaft, and stator windings of a plurality of phases that are provided in
the slots and wound around the stator core by concentrated winding, in
which a rotating magnetic field including harmonics components is formed
when AC currents flow through the stator windings; andthe rotor includes
a rotor core, rotor windings wound around the rotor core to generate an
induced electromotive force when interlinked with the rotating magnetic
field including the harmonics components formed by the stator, and a
rectifying element that rectifies currents flowing through the rotor
windings in response to generation of the induced electromotive
force;wherein the rotor core includes a plurality of magnetic pole
portions, around which the rotor windings are wound, which can function
as magnets where the magnetic pole is fixed, the magnetic pole portions
are magnetized when the currents rectified by the rectifying element flow
through the rotor windings, the magnetic pole portions are disposed in
spaced confronting relationship with the stator in a state where the
magnetic pole portions are spaced apart from each other in the
circumferential direction, andthe rotor windings are wound around
respective magnetic pole portions by short-pitch winding.

2. The rotary electric machine according to claim 1, whereinthe width of
the rotor winding wound around each magnetic pole portion in the
circumferential direction is substantially equal to a width corresponding
to an electric angle of 90.degree..

3. The rotary electric machine according to claim 1, whereineach magnetic
pole portion of the rotor core has a magnetic resistance that is smaller
than a magnetic resistance of a portion corresponding to a position
between magnetic pole portions in the circumferential direction.

4. The rotary electric machine according to claim 1,wherein each magnetic
pole portion of the rotor core projects toward the stator.

5. The rotary electric machine according to claim 1, whereinthe rotor
includes a permanent magnet provided at a portion corresponding to a
position between magnetic pole portions in the circumferential direction.

6. The rotary electric machine according to claim 1, whereinthe rotor
windings wound around respective magnetic pole portions are electrically
isolated from each other,the rectifying element is provided for each of
the rotor windings that are electrically isolated, andrespective
rectifying elements rectify currents that flow through the rotor windings
wound around respective magnetic pole portions in such a manner that
magnetic poles of the magnetic pole portions alternate in the
circumferential direction.

7. The rotary electric machine according to claim 1, whereinrotor windings
wound around the magnetic pole portions that are adjacent to each other
in the circumferential direction are electrically isolated from each
other,the rectifying element is provided for each of the rotor windings
that are electrically isolated, andrespective rectifying elements rectify
currents that flow through rotor windings wound around the magnetic pole
portions, which are adjacent to each other in the circumferential
direction, in such a way as to differentiate directions of the magnetic
poles of the neighboring magnetic pole portions.

8. The rotary electric machine according to claim 7, whereinrotor windings
wound around the magnetic pole portions that can function as magnets
having the same magnetic pole are electrically connected.

9. A rotary electric machine including a stator and a rotor that are
disposed in spaced confronting relationship, whereinthe stator includes a
stator core on which a plurality of slots are formed and spaced apart
from each other in a circumferential direction around a rotor rotational
shaft, and stator windings of a plurality of phases that are provided in
the slots and wound around the stator core by concentrated winding, in
which a rotating magnetic field including harmonics components is formed
when AC currents flow through the stator windings; andthe rotor includes
a rotor core, rotor windings wound around the rotor core to generate an
induced electromotive force when interlinked with the rotating magnetic
field including the harmonics components formed by the stator, and a
rectifying element that rectifies currents flowing through the rotor
windings in response to generation of the induced electromotive
force;wherein the rotor core includes a plurality of magnetic pole
portions, which can function as magnets where the magnetic pole is fixed,
the magnetic pole portions are magnetized when the currents rectified by
the rectifying element flow through the rotor windings, the magnetic pole
portions are disposed in spaced confronting relationship with the stator
in a state where the magnetic pole portions are spaced apart from each
other in the circumferential direction, andthe width of each magnetic
pole portion in the circumferential direction is smaller than a width
corresponding to an electric angle of 180.degree..

10. The rotary electric machine according to claim 9, whereinthe width of
each magnetic pole portion in the circumferential direction is
substantially equal to a width corresponding to an electric angle of
90.degree..

11. The rotary electric machine according to claim 9, whereinthe rotor
core further includes an annular core portion,the rotor windings are
wound around the annular core portion by toroidal winding, andeach
magnetic pole portion projects from the annular core portion toward the
stator.

12. A rotary electric machine including a stator and a rotor that are
disposed in spaced confronting relationship, whereinthe stator includes a
stator core on which a plurality of slots are formed and spaced apart
from each other in a circumferential direction around a rotor rotational
shaft, and stator windings of a plurality of phases that are provided in
the slots and wound around the stator core by concentrated winding, in
which a rotating magnetic field including harmonics components is formed
when AC currents flow through the stator windings; andthe rotor includes
a rotor core, rotor windings wound around the rotor core to generate an
induced electromotive force when interlinked with the rotating magnetic
field including the harmonics components formed by the stator, and a
rectifying element that rectifies currents flowing through the rotor
windings in response to generation of the induced electromotive
force;wherein the rotor core includes a plurality of magnetic pole
portions that can function as magnets where the magnetic pole is fixed,
the magnetic pole portions are magnetized when the currents rectified by
the rectifying element flow through the rotor windings, the magnetic pole
portions are disposed in spaced confronting relationship with the stator
in a state where the magnetic pole portions are spaced apart from each
other in the circumferential direction,the rotor windings are a common
rotor winding wound around each magnetic pole portion, anddirections of
winding portions of the common rotor winding, which are wound around
magnetic pole portions that are adjacent to each other in the
circumferential direction, are opposite each other.

13. The rotary electric machine according to claim 12, whereinthe width of
the rotor winding wound around each magnetic pole portion is set to be
larger than a width corresponding to an electric angle of 90.degree. in
the circumferential direction and smaller than a width corresponding to
an electric angle of 120.degree..

14. A driving controller for a rotary electric machine, comprising:the
rotary electric machine defined in claim 1; anda control unit that
controls the phase of AC currents that flow through the stator windings
to control the torque of the rotor.

15. A driving controller for a rotary electric machine, comprising:the
rotary electric machine defined in claim 9; anda control unit that
controls the phase of AC currents that flow through the stator windings
to control the torque of the rotor.

16. A driving controller for a rotary electric machine, comprising:the
rotary electric machine defined in claim 12; anda control unit that
controls the phase of AC currents that flow through the stator windings
to control the torque of the rotor.

Description:

TECHNICAL FIELD

[0001]The present invention relates to a rotary electric machine including
a stator and a rotor that are disposed in spaced confronting
relationship, and to a driving controller for the rotary electric
machine.

BACKGROUND ART

[0002]A brushless power generator disclosed in the following Patent
Document 1 includes a main power generation winding and an exciting
winding that are wound around a stator, a field winding and an auxiliary
field winding that are wound around a rotor, a diode that short-circuits
the exciting winding of the stator, and a rectifier that rectifies a
current flowing from the auxiliary field winding to the field winding of
the rotor. According to Patent Document 1, when the rotor starts
rotating, an induced voltage is generated on the exciting winding of the
stator due to a residual magnetism of a field core of the rotor. Exciting
current flows in one direction via the diode and a static magnetic field
is generated on the stator. As the rotor rotates in the static magnetic
field, an induced voltage is generated on the auxiliary field winding
wound around the field core of the rotor. Field current rectified by the
rectifier flows through the field winding. Therefore, magnetic poles of
N-poles and S-poles are generated on the rotor.

[0003]The following Patent Document 2 discloses a reactor connected to a
main power generation winding of a stator, which is arranged as a
concentrated full-pitch winding, instead of providing the above-described
exciting winding on the stator. According to Patent Document 2, when the
rotor starts rotating, a residual field of a rotor core induces an
electromotive force on the main power generation winding of the stator.
The induced electromotive force causes a reactor exciting current that
flows, as armature current, in a closed circuit including the main power
generation winding and the reactor. As a result, an armature reaction
magnetic field is generated. In this case, because the main power
generation winding of the stator is the concentrated full-pitch winding,
the generated armature reaction magnetic field includes harmonics
components (a fifth space harmonics magnetic field). The armature
reaction magnetic field including the fifth space harmonics magnetic
field interlinks with the auxiliary field winding of the rotor.
Accordingly, an electromotive force is generated on the auxiliary field
winding. A diode bridge circuit converts the generated electromotive
force into a direct current that can be supplied as field current to a
field winding of the rotor. Therefore, magnetic poles of N-poles and
S-poles are generated on the rotor.

[0004]The following Patent Document 3 discloses an arrangement that does
not include the above-described auxiliary field winding of the rotor and,
instead, uses a diode that short-circuits a full-pitch field winding of
the rotor. According to Patent Document 3, when the rotor starts
rotating, a residual field of a rotor core induces an electromotive force
on the main power generation winding of the stator. The induced
electromotive force causes a reactor exciting current that flows, as
armature current, in a closed circuit including the main power generation
winding and the reactor. As a result, an armature reaction magnetic field
is generated. Further, an electromotive force is induced on the field
winding of the rotor that is magnetically connected to odd-order space
harmonics components of the armature reaction magnetic field. Field
current rectified by the diode flows through the field winding. As a
result, magnetic poles of N-poles and S-poles are generated on the rotor.
Further, the following Patent Document 4 discloses a parallel connection
of the above-described full-pitch field windings of the rotor for the
purpose of increasing the field current that flows through the field
winding.

[0005]According to Patent Documents 1 and 2, the exciting winding or the
reactor is provided on the stator in addition to the main power
generation winding. Further, the auxiliary field winding is provided on
the rotor in addition to the field winding. Therefore, the winding
structure tends to be complicated, and downsizing the entire winding
structure becomes difficult. According to Patent Documents 3 and 4, the
auxiliary field winding of the rotor is omitted because the field winding
of the rotor is short-circuited via the diode. However, the exciting
winding or the reactor is provided on the stator in addition to the main
power generation winding. Therefore, the winding structure tends to be
complicated. Further, according to Patent Documents 3 and 4, it is
difficult to efficiently generate the electromotive force, which is
induced by the space harmonics components, on the field winding of the
rotor, because the field winding of the rotor is a full-pitch winding. It
is therefore necessary to use the exciting winding or the reactor of the
stator, other than the main power generation winding, to generate the
electromotive force to be induced by the space harmonics components on
the field winding of the rotor.

[0006]Patent Document 1: JP 62-23348 A

[0007]Patent Document 2: JP 4-285454 A

[0008]Patent Document 3: JP 8-65976 A

[0009]Patent Document 4: JP 11-220857 A

DISCLOSURE OF THE INVENTION

[0010]The present invention has an advantage to efficiently generate the
electromotive force to be induced by the harmonics components on the
rotor winding and efficiently increase the torque of the rotor. Further,
the present invention has another advantage to simplify the winding
structure of a rotary electric machine.

[0011]A rotary electric machine according to the present invention
includes a stator and a rotor, which are disposed in spaced confronting
relationship. The stator includes a stator core on which a plurality of
slots are formed and spaced apart from each other in a circumferential
direction around a rotor rotational shaft, and stator windings of a
plurality of phases that are provided in the slots and wound around the
stator core by concentrated winding, in which a rotating magnetic field
including harmonics components is formed when AC currents flow through
the stator windings. The rotor includes a rotor core, rotor windings
wound around the rotor core to generate an induced electromotive force
when interlinked with the rotating magnetic field including the harmonics
components formed by the stator, and a rectifying element that rectifies
currents flowing through the rotor windings in response to generation of
the induced electromotive force. The rotor core includes a plurality of
magnetic pole portions, around which the rotor windings are wound, which
can function as magnets where the magnetic pole is fixed. The magnetic
pole portions are magnetized when the currents rectified by the
rectifying element flow through the rotor windings. The magnetic pole
portions are disposed in spaced confronting relationship with the stator
in a state where the magnetic pole portions are spaced apart from each
other in the circumferential direction. Further, the rotor windings are
wound around respective magnetic pole portions by short-pitch winding.

[0012]According to an aspect of the present invention, it is preferable
that the width of the rotor winding wound around each magnetic pole
portion in the circumferential direction is substantially equal to a
width corresponding to an electric angle of 90°.

[0013]According to an aspect of the present invention, it is preferable
that each magnetic pole portion of the rotor core has a magnetic
resistance that is smaller than a magnetic resistance of a portion
corresponding to a position between magnetic pole portions in the
circumferential direction. Further, according to an aspect of the present
invention, it is preferable that each magnetic pole portion of the rotor
core projects toward the stator. Further, according to an aspect of the
present invention, it is preferable that the rotor includes a permanent
magnet provided at a portion corresponding to a position between magnetic
pole portions in the circumferential direction.

[0014]According to an aspect of the present invention, it is preferable
that the rotor windings wound around respective magnetic pole portions
are electrically isolated from each other, the rectifying element is
provided for each of the rotor windings that are electrically isolated,
and respective rectifying elements rectify currents that flow through the
rotor windings wound around respective magnetic pole portions in such a
manner that magnetic poles of the magnetic pole portions alternate in the
circumferential direction.

[0015]According to an aspect of the present invention, it is preferable
that the rotor windings wound around the magnetic pole portions that are
adjacent to each other in the circumferential direction are electrically
isolated from each other, the rectifying element is provided for each of
the rotor windings that are electrically isolated, and respective
rectifying elements rectify currents that flow through rotor windings
wound around the magnetic pole portions, which are adjacent to each other
in the circumferential direction, in such a way as to differentiate
directions of the magnetic poles of the neighboring magnetic pole
portions. In this case, it is preferable that rotor windings wound around
the magnetic pole portions that can function as magnets having the same
magnetic pole are electrically connected.

[0016]Further, a rotary electric machine according to the present
invention includes a stator and a rotor, which are disposed in spaced
confronting relationship. The stator includes a stator core on which a
plurality of slots are formed and spaced apart from each other in a
circumferential direction around a rotor rotational shaft, and stator
windings of a plurality of phases that are provided in the slots and
wound around the stator core by concentrated winding, in which a rotating
magnetic field including harmonics components is formed when AC currents
flow through the stator windings. The rotor includes a rotor core, rotor
windings wound around the rotor core to generate an induced electromotive
force when interlinked with the rotating magnetic field including the
harmonics components formed by the stator, and a rectifying element that
rectifies currents flowing through the rotor windings in response to
generation of the induced electromotive force. The rotor core includes a
plurality of magnetic pole portions, which can function as magnets where
the magnetic pole is fixed. The magnetic pole portions are magnetized
when the currents rectified by the rectifying element flow through the
rotor windings. The magnetic pole portions are disposed in spaced
confronting relationship with the stator in a state where the magnetic
pole portions are spaced apart from each other in the circumferential
direction. Further, the width of each magnetic pole portion in the
circumferential direction is smaller than a width corresponding to an
electric angle of 180°.

[0017]According to an aspect of the present invention, it is preferable
that the width of each magnetic pole portion in the circumferential
direction is substantially equal to a width corresponding to an electric
angle of 90°.

[0018]According to an aspect of the present invention, it is preferable
that the rotor core further includes an annular core portion, the rotor
windings are wound around the annular core portion by toroidal winding,
and each magnetic pole portion projects from the annular core portion
toward the stator.

[0019]Further, a rotary electric machine according to the present
invention includes a stator and a rotor, which are disposed in spaced
confronting relationship. The stator includes a stator core on which a
plurality of slots are formed and spaced apart from each other in a
circumferential direction around a rotor rotational shaft, and stator
windings of a plurality of phases that are provided in the slots and
wound around the stator core by concentrated winding, in which a rotating
magnetic field including harmonics components is formed when AC currents
flow through the stator windings. The rotor includes a rotor core, rotor
windings wound around the rotor core to generate an induced electromotive
force when interlinked with the rotating magnetic field including the
harmonics components formed by the stator, and a rectifying element that
rectifies currents flowing through the rotor windings in response to
generation of the induced electromotive force. The rotor core includes a
plurality of magnetic pole portions that can function as magnets where
the magnetic pole is fixed. The magnetic pole portions are magnetized
when the currents rectified by the rectifying element flow through the
rotor windings. The magnetic pole portions are disposed in spaced
confronting relationship with the stator in a state where the magnetic
pole portions are spaced apart from each other in the circumferential
direction. The rotor windings are a common rotor winding wound around
each magnetic pole portion. Further, directions of winding portions of
the common rotor winding, which are wound around magnetic pole portions
that are adjacent to each other in the circumferential direction, are
opposite each other.

[0020]According to an aspect of the present invention, it is preferable
that the width of the rotor winding wound around each magnetic pole
portion is set to be larger than a width corresponding to an electric
angle of 90° in the circumferential direction and smaller than a
width corresponding to an electric angle of 120°.

[0021]Moreover, a driving controller for a rotary electric machine
according to the present invention includes the rotary electric machine
according to the present invention, and a control unit that controls the
phase of AC currents that flow through the stator windings to thereby
control the torque of the rotor.

[0022]According to the present invention, the electromotive force to be
induced by the harmonics components generated by the rotor windings can
be efficiently increased. The magnetic flux of the magnet to be generated
on each magnetic pole portion by the current that flows through the rotor
winding can be efficiently increased. As a result, the torque of the
rotor can be efficiently increased. Further, according to the present
invention, the electromotive force to be induced by the harmonics
components can be generated on the rotor windings without providing any
type of winding other than the stator windings on the stator, and without
providing any type of winding other than the rotor windings on the rotor.
As a result, the type of the winding to be provided on each of the stator
and the rotor can be simplified into one type. Thus, the winding
structure of a rotary electric machine can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a view illustrating a schematic configuration of a rotary
electric machine according to an embodiment of the present invention.

[0024]FIG. 2 is a view illustrating a schematic configuration of the
rotary electric machine according to an embodiment of the present
invention.

[0025]FIG. 3 is a view illustrating a schematic configuration of the
rotary electric machine according to an embodiment of the present
invention.

[0026]FIG. 4A illustrates a calculation result of a flux linkage to be
caused by space harmonics that interacts with rotor windings.

[0027]FIG. 4B illustrates a calculation result of a flux linkage to be
caused by space harmonics that interacts with rotor windings.

[0028]FIG. 5 illustrates a calculation result of the amplitude of a flux
linkage that interacts with rotor windings, which can be obtained by
changing a circumferential width θ of the rotor winding.

[0029]FIG. 6 illustrates a calculation result of the torque of a rotor,
which can be obtained by changing the phase of an AC current that flows
through a stator winding.

[0030]FIG. 7 illustrates a calculation result of the torque of a rotor,
which can be obtained by changing the phase of an AC current that flows
through a stator winding.

[0031]FIG. 8 is a view illustrating a schematic configuration of a driving
controller for the rotary electric machine according to an embodiment of
the present invention.

[0032]FIG. 9 is a view illustrating another schematic configuration of a
rotary electric machine according to an embodiment of the present
invention.

[0033]FIG. 10 is a view illustrating another schematic configuration of a
rotary electric machine according to an embodiment of the present
invention.

[0034]FIG. 11 is a view illustrating another schematic configuration of a
rotary electric machine according to an embodiment of the present
invention.

[0035]FIG. 12 is a view illustrating another schematic configuration of a
rotary electric machine according to an embodiment of the present
invention.

[0036]FIG. 13 is a view illustrating another schematic configuration of a
rotary electric machine according to an embodiment of the present
invention.

[0037]FIG. 14 illustrates a calculation result of the amplitude of a flux
linkage that interacts with rotor windings, which can be obtained by
changing a circumferential width θ of the rotor winding.

[0038]FIG. 15 is a view illustrating another schematic configuration of a
rotary electric machine according to an embodiment of the present
invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0039]Preferred embodiments of the present invention are described below
with reference to the attached drawings.

[0040]FIGS. 1 to 3 are views illustrating a schematic configuration of a
rotary electric machine 10 according to an embodiment of the present
invention. FIG. 1 schematically illustrates an assembled configuration of
a stator 12 and a rotor 14, which are seen from a direction parallel to a
rotor rotational shaft 22. FIG. 2 schematically illustrates a
configuration of the stator 12. FIG. 3 schematically illustrates a
configuration of the rotor 14. The rotary electric machine 10 according
to the present embodiment includes the stator 12 fixed to a casing (not
illustrated), and the rotor 14 that is rotatable relative to the stator
12 and is disposed in spaced confronting relationship with the stator 12
via a predetermined gap. The example illustrated in FIGS. 1 to 3 is a
radial type rotary electric machine, according to which the stator 12 and
the rotor 14 are disposed in spaced confronting relationship in a radial
direction perpendicular to the rotational shaft 22 (hereinafter, simply
referred to as "radial direction"). The rotor 14 is disposed on the inner
side of the stator 12 in the radial direction.

[0041]The stator 12 includes a stator core 26 and multiple-phase (more
specifically, odd-phase (e.g., three-phase)) stator windings 28u, 28v,
and 28w that are provided on the stator core 26. The stator core 26
includes a plurality of teeth 30 that project inward in the radial
direction (i.e., toward the rotor 14) and are spaced apart from each
other in the circumferential direction around the rotational shaft 22
(hereinafter, simply referred to as "circumferential direction"). A slot
31 is formed between two teeth 30. More specifically, a plurality of
slots 31 are formed on the stator core 26 along the circumferential
direction while being spaced apart from each other. The stator windings
28u, 28v, and 28w of respective phases are located in the slots 31 and
are wound around the teeth 30 by concentrated short-pitch winding. The
teeth 30 and the stator windings 28u, 28v, and 28w wound around the teeth
30 constitute magnetic poles. When multiple-phase (e.g., three-phase or
odd-phase) AC currents flow through the multiple-phase (e.g., three-phase
or odd-phase) stator windings 28u, 28v, and 28w, the teeth 30 arrayed in
the circumferential direction are sequentially magnetized. Thus, a
rotating magnetic field that rotates in the circumferential direction is
formed on the teeth 30. The rotating magnetic field formed on the teeth
30 acts on the rotor 14 from the front end surface of the teeth 30. In
the example illustrated in FIG. 2, three teeth 30 and a set of
three-phase (i.e., u-phase, v-phase, and w-phase) stator windings 28u,
28v, and 28w wound around three teeth 30 configures a pair of poles. As a
result, four-pole three-phase stator windings 28u, 28v, and 28w are wound
around respective teeth 30. The number of pairs of poles on the stator 12
is four pairs of poles.

[0042]The rotor 14 includes a rotor core 16 and a plurality of rotor
windings 18n and 18s provided on the rotor core 16. A plurality of
salient poles 19 projecting outward (i.e., toward the stator 12) in the
radial direction are arranged on the rotor core 16 along the
circumferential direction while being spaced apart from each other. Each
salient pole 19 opposes the stator 12 (i.e., the teeth 30). A magnetic
resistance acting on the rotor 14 when the magnetic flux of the stator 12
(i.e., the teeth 30) passes through the rotor 14 is variable in the
rotational direction by the salient pole 19. The magnetic resistance
becomes smaller at a position corresponding to each salient pole 19 in
the rotational direction. The magnetic resistance becomes larger at a
position (e.g., midpoint) between two neighboring salient poles 19 in the
rotational direction. The rotor windings 18n and 18s are wound around
these salient poles 19 so that the rotor windings 18n and the rotor
windings 18s are alternately disposed in the circumferential direction.
Each of the rotor windings 18n and 18s has a winding center-axis that
corresponds to the radial direction. As illustrated in FIG. 3, a d-axis
magnetic path is a magnetic path that passes through the position between
two neighboring salient poles 19 where the magnetic resistance is large.
A q-axis magnetic path is a magnetic path that passes through the salient
pole 19 itself where the magnetic resistance is small. Each of the rotor
windings 18n and 18s is disposed around the q-axis magnetic path where
the magnetic resistance is small. In the example illustrated in FIG. 3,
the rotor windings 18n and 18s wound around respective salient poles 19
are electrically disconnected and isolated (i.e., insulated). Diodes 21n
and 21s (i.e., rectifying elements) are connected between two terminal
ends of respective rotor windings 18n and 18s that are electrically
isolated from each other. Each rotor winding 18n is short-circuited via
the diode 21n. Thus, the current that flows through the rotor winding 18n
can be rectified by the diode 21n so as to flow in one direction.
Similarly, each rotor winding 18s is short-circuited via the diode 21s.
Thus, the current that flows through the rotor winding 18s can be
rectified by the diode 21s so as to flow in one direction. In the present
embodiment, directions of the diodes 21n and 21s connected to the rotor
windings 18n and 18s are opposite each other. Therefore, current flowing
directions (i.e., rectifying directions regulated by the diodes 21n and
21s) are opposite each other between the rotor windings 18n and the rotor
windings 18s that are alternately disposed in the circumferential
direction.

[0043]When a DC current flows through the rotor winding 18n according to
the rectifying direction of the diode 21n, the salient pole 19 around
which the rotor winding 18n is wound can be magnetized. Therefore, the
salient pole 19 can function as a magnet where the magnetic pole is fixed
(i.e., a magnetic pole portion). Similarly, when a DC current flows
through the rotor winding 18s according to the rectifying direction of
the diode 21s, the salient pole 19 around which the rotor winding 18s is
wound can be magnetized. Therefore, the salient pole 19 can function as a
magnet where the magnetic pole is fixed (i.e., a magnetic pole portion).
The directions of the DC currents that flow through the rotor winding 18n
and the rotor winding 18s, which are adjacent to each other in the
circumferential direction, are opposite each other. Therefore, magnetized
directions of two salient poles 19, which are adjacent to each other in
the circumferential direction, are opposite each other. Magnets having
mutually different magnetic poles can be formed on two salient poles 19.
The magnetic poles of the salient poles 19 alternate in the
circumferential direction. In the present embodiment, an N-pole is formed
on the salient pole 19 around which the rotor winding 18n is wound.
Further, an S-pole is formed on the salient pole 19 around which the
rotor winding 18s is wound. To this end, the setting for the diodes 21n
and 21s is performed to adjust the current rectifying directions of the
rotor windings 18n and 18s. In this manner, the magnets are formed on
respective salient poles 19 so that the N-poles and the S-poles are
alternately arrayed in the circumferential direction. Further, two
salient poles 19 (i.e., the N-pole and the S-pole) that are adjacent to
each other in the circumferential direction can constitute a pair of
poles. According to the example illustrated in FIG. 3, the rotor 14
includes a total of eight salient poles 19. The number of pairs of poles
on the rotor 14 is four pairs of poles. Therefore, according to the
example illustrated in FIGS. 1 to 3, the number of pairs of poles on the
stator 12 is four pairs of poles while the number of pairs of poles on
the rotor 14 is four pairs of poles. In this respect, the number of pairs
of poles on the stator 12 is equal to the number of pairs of poles on the
rotor 14. However, the number of pairs of poles on the stator 12 and the
number of pairs of poles on the rotor 14 can be any number other than
four pairs of poles.

[0044]In the present embodiment, the width of each salient pole 19 in the
circumferential direction is set to be shorter than a width corresponding
to an electric angle of 180° of the rotor 14. Further, the width
θ of respective rotor windings 18n and 18s in the circumferential
direction is set to be shorter than the width corresponding to an
electric angle of 180° of the rotor 14. The rotor windings 18n and
18s are wound around the salient poles 19 by short-pitch winding.
Regarding the width θ of respective rotor windings 18n and 18s, it
may be useful to regulate the distance between the centers of the cross
sections of the rotor windings 18n and 18s in consideration of the
cross-sectional areas of respective rotor windings 18n and 18s. More
specifically, the width θ of respective rotor windings 18n and 18s
can be expressed using an average value obtainable from a gap between
inner circumferential surfaces of the rotor windings 18n and 18s and a
gap between outer circumferential surfaces of the rotor windings 18n and
18s. The electric angle of the rotor 14 can be expressed using a value
that is obtainable by multiplying the mechanical angle of the rotor 14 by
the number of pairs of poles p (p=4 according to the example illustrated
in FIG. 3) of the rotor 14 (namely, electric angle=mechanical
angle×p). Therefore, the width θ of respective rotor windings
18n and 18s in the circumferential direction satisfies the following
formula (1) when "r" represents a distance from the center of the
rotational shaft 22 to the rotor windings 18n and 18s.

θ<π×r/p (1)

[0045]In the present embodiment, the magnetomotive force that causes the
stator 12 to generate the rotating magnetic field has a distribution that
is not similar to a sine wave distribution (including only the basic
wave), because of the layout of the stator windings 28u, 28v, and 28w of
respective phases and the shape of the stator core 26 that includes the
teeth 30 and the slots 31. The distribution of the magnetomotive force
that causes the stator 12 to generate the rotating magnetic field
includes harmonics components. Particularly, according to the
concentrated winding, the stator windings 28u, 28v, and 28w of respective
phases are not overlapped with each other. Therefore, the harmonics
components appearing in the magnetomotive force distribution of the
stator 12 increase in amplitude level. Further, for example, in a case
where the stator windings 28u, 28v, and 28w are three-phase concentrated
windings, input electric frequency tertiary components increase as
harmonics components increase in amplitude level. In the following
description, the harmonics components that may be caused in the
magnetomotive force due to the layout of the stator windings 28u, 28v,
and 28w and the shape of the stator core 26 are referred to as space
harmonics.

[0046]The rotating magnetic field (basic wave component) formed on the
teeth 30 interacts with the rotor 14 when three-phase AC currents flow
through the three-phase stator windings 28u, 28v, and 28w.
Correspondingly, the salient poles 19 are magnetically attracted by the
rotating magnetic field of the teeth 30 in such a manner that the
magnetic resistance of the rotor 14 becomes smaller. Accordingly, a
torque (i.e., a reluctance torque) acts on the rotor 14. The rotor 14
rotates in synchronization with the rotating magnetic field (basic wave
component) produced by the stator 12.

[0047]Further, when the rotating magnetic field produced by the teeth 30,
which includes space harmonics components, interlinks with the rotor
windings 18n and 18s of the rotor 14, the rotor windings 18n and 18s are
subjected to magnetic flux variations that are caused by the space
harmonics components at a frequency that is different from the rotation
frequency (i.e., basic wave component of the rotating magnetic field) of
the rotor 14. The above-described magnetic flux variations cause
respective rotor windings 18n and 18s to produce induced electromotive
forces. Currents that flow through the rotor windings 18n and 18s in
accordance with the generation of the induced electromotive force are
rectified by respective diodes 21n and 21s. Therefore, these currents
flow in one direction (as DC currents). Further, when the DC currents
rectified by respective diodes 21n and 21s flow through the rotor
windings 18n and 18s, the salient poles 19 are magnetized
correspondingly. Accordingly, magnets each having a magnetic pole (either
the N-pole or the S-pole) are produced on the salient poles 19. As
described above, the current rectifying directions of the rotor windings
18n and 18s, which are regulated by the diodes 21n and 21s, are opposite
each other. Therefore, the magnets produced on respective salient poles
19 are arranged in such a manner that N-poles and S-poles are alternately
disposed in the circumferential direction. Further, when the magnetic
field of each salient pole 19 (i.e., the magnet where the magnetic pole
is fixed) interacts with the rotating magnetic field (i.e., basic wave
component) of the teeth 30, attractive and repulsive functions are
generated. The electromagnetic interaction (i.e., the attractive and
repulsive functions) between the rotating magnetic field (basic wave
component) of the teeth 30 and the magnetic field of the salient poles 19
(magnets) generates a torque (i.e., a torque that corresponds to a
magnetic torque) that acts on the rotor 14. Therefore, the rotor 14
rotates in synchronization with the rotating magnetic field (basic wave
component) formed by the stator 12. As described above, the rotary
electric machine 10 according to the present embodiment can function as a
motor that generates motive power (i.e., mechanical power) from the rotor
14 when electric power is supplied to the stator windings 28u, 28v, and
28w. Meanwhile, the rotary electric machine 10 according to the present
embodiment can function as an electric power generator that generates
electric power from the stator windings 28u, 28v, and 28w when the rotor
14 generates motive power.

[0048]FIGS. 4A and 4B illustrate calculation results of the flux linkage
interacting with the rotor windings 18n and 18s that may be generated by
the space harmonics. Each waveform illustrated in FIG. 4A represents a
waveform of the flux linkage that interacts with rotor windings 18n and
18s when the phase (i.e., the current vector phase relative to the rotor
position) of respective AC currents flowing through the stator windings
28u, 28v, and 28w is changed. Further, FIG. 42 represents a result of
frequency analysis performed on the waveform of the flux linkage that
interacts with the rotor windings 18n and 18s. From the frequency
analysis result illustrated in FIG. 42, it is understood that input
electric frequency tertiary components are mainly generated. As
illustrated in FIG. 4A, the flux linkage waveform does not substantially
change even when the current vector phase is changed, although the bias
of the flux linkage is variable.

[0049]The amplitude (i.e. variation width) of a flux linkage that
interacts with the rotor windings 18n and 18s is influenced by the width
θ of respective rotor windings 18n and 18s in the circumferential
direction. FIG. 5 illustrates a calculation result of the amplitude
(i.e., variation width) of a flux linkage that interacts with the rotor
windings 18n and 18s, which can be obtained by changing the width θ
of the rotor windings 18n and 18s in the circumferential direction. In
FIG. 5, the coil width θ is expressed using a value converted into
an electric angle. As illustrated in FIG. 5, the variation width of the
flux linkage that interacts with the rotor windings 18n and 18s increases
when the coil width θ decreases from the angle 180°.
Therefore, the amplitude of the flux linkage generated by the space
harmonics can be increased by setting the coil width θ to be
smaller than the angle 180°; more specifically, by winding the
rotor windings 18n and 18s by short-pitch winding, as compared with the
case of full-pitch winding.

[0050]Accordingly, in the present embodiment, the induced electromotive
forces to be generated by the space harmonics on the rotor windings 18n
and 18s can be efficiently increased by setting the width of each salient
pole 19 to be smaller than the width corresponding to an electric angle
of 180° in the circumferential direction and further by winding
the rotor windings 18n and 18s around the salient poles 19 by short-pitch
winding. Therefore, the present embodiment can efficiently generate
induced currents that flow through the rotor windings 18n and 18s by
utilizing the space harmonics that do not substantially contribute to the
generation of torque. The present embodiment can efficiently increase the
magnetic fluxes of the magnets on the salient poles 19 that are generated
by the induced currents. As a result, the torque that acts on the rotor
14 can be efficiently increased. Further, the present embodiment can
efficiently generate the electromotive forces to be induced by the space
harmonics on the rotor windings 18n and 18s without providing any type of
winding (e.g., the exciting winding or the reactor discussed in the
Patent Documents 1 to 4) other than the stator windings 28u, 28v, and 28w
on the stator 12. Therefore, the windings to be provided on the stator 12
can be simplified into only one type (i.e., only the stator windings 28u,
28v, and 28w). As a result, the winding structure of the stator 12 can be
simplified. Further, by rectifying the induced current to be caused by
the induced electromotive force with the diodes 21n and 21s, the magnet
where the magnetic pole is fixed can be generated on the rotor 14 (i.e.,
each salient pole 19) without providing any type of winding (e.g., the
auxiliary field winding discussed in the Patent Documents 1 and 2) other
than the rotor windings 18n and 18s on the rotor 14. Therefore, the
windings to be provided on the rotor 14 can be simplified into only one
type (only the rotor windings 18n and 18s). The winding structure of the
rotor 14 can be simplified. As a result, the winding structure of the
rotary electric machine 10 can be simplified, and the rotary electric
machine 10 can be downsized.

[0051]Further, as illustrated in FIG. 5, the amplitude of the flux linkage
generated by the space harmonics can be maximized when the coil width
θ is 90°. Accordingly, in the present embodiment, to further
increase the amplitude of the flux linkage generated by the space
harmonics that interacts with the rotor windings 18n and 18s, the width
θ of the rotor windings 18n and 18s in the circumferential
direction is preferably equal to (or substantially equal to) the width
corresponding to an electric angle of 90° of the rotor 14.
Therefore, it is preferable that the width θ of the rotor windings
18n and 18s in the circumferential direction satisfies (or substantially
satisfies) the following formula (2).

θ=π×r/(2×p) (2)

[0052]As described above, the induced electromotive forces to be generated
by the space harmonics on the rotor windings 18n and 18s can be maximized
by setting the width θ of the rotor windings 18n and 18s in the
circumferential direction equal to (or substantially equal to) the width
corresponding to the electric angle of 90°. Therefore, the present
embodiment can most efficiently increase the magnetic fluxes of the
magnets on the salient poles 19, which are generated by the induced
currents. As a result, the torque acting on the rotor 14 can be increased
further efficiently.

[0053]FIGS. 6 and 7 illustrate calculation results of the torque of the
rotor 14, which can be obtained by changing the phase (i.e., current
vector phase relative to the rotor position) of respective AC currents
that flow through the stator windings 28u, 28v, and 28w. FIG. 6
illustrates a calculation result of the torque in a case where the
amplitude (i.e., current amplitude) and the phase (i.e., current vector
phase) of respective AC currents flowing through the stator windings 28u,
28v, and 28w are changed while the rotational speed of the rotor 14 is
maintained at a constant speed. FIG. 7 illustrates calculation results of
the torque in a case where the current vector phase and the rotational
speed of the rotor 14 are changed while the current amplitude is
maintained at a constant level. As understood from FIGS. 6 and 7, if the
current vector phase changes, the torque of the rotor 14 changes
correspondingly. Therefore, the torque of the rotor 14 can be controlled
by controlling the current vector phase (i.e., the phases of the AC
currents that flow through the stator windings 28u, 28v, and 28w).
Further, as understood from FIG. 6, if the current amplitude changes, the
torque of the rotor 14 changes correspondingly. Therefore, the torque of
the rotor 14 can be controlled by controlling the current amplitude
(i.e., the amplitude of the AC currents that flow through the stator
windings 28u, 28v, and 28w). Further, as understood from FIG. 7, if the
rotational speed of the rotor 19 changes, the torque of the rotor 14
changes correspondingly. Therefore, the torque of the rotor 14 can be
controlled by controlling the rotational speed of the rotor 14.

[0054]FIG. 8 illustrates a schematic configuration of a driving controller
for the rotary electric machine 10 according to the present embodiment.
An electric power storage device 42 is a DC power source having the
capability of charging and discharging electric power. The electric power
storage device 42 is, for example, constituted by a secondary battery. An
inverter 40 includes switching elements (not illustrated) that perform
switching operations for converting the DC power of the electric power
storage device 42 into a plurality of phases of alternating currents
(e.g., three-phase alternating currents). Thus, the inverter 40 can
supply alternating currents to respective phases of the stator windings
28u, 28v, and 28w. A control unit 41 controls the torque of the rotor 14
by controlling the phase (current vector phases) of respective AC
currents that flow through the stator windings 28u, 28v, and 28w. To this
end, the control unit 41 controls the switching operation of respective
switching elements of the inverter 40. However, to control the torque of
the rotor 14, the control unit 41 can control the amplitude of the AC
currents that flow through the stator windings 28u, 28v, and 28w, or can
control the rotational speed of the rotor 14.

[0055]Another example configuration of the rotary electric machine 10
according to the present embodiment is described below.

[0056]In the present embodiment, for example, as illustrated in FIG. 9,
the magnetic resistance of the rotor 14 can be changed in the rotational
direction by forming slits (i.e., gaps) 44 on the rotor core 16. As
illustrated in FIG. 9, the rotor core 16 includes d-axis magnetic path
portions 39 where the magnetic path has a larger magnetic resistance and
q-axis magnetic path portions 29 where the magnetic path has a smaller
magnetic resistance compared to that of the d-axis magnetic path portions
39. Formation of the slits 44 realizes an arrangement of the d-axis
magnetic path portions 39 and the q-axis magnetic path portions 29 that
are alternately disposed in the circumferential direction, in a state
where the d-axis magnetic path portions 39 and the q-axis magnetic path
portions 29 are disposed in spaced confronting relationship with the
stator 12 (i.e., the teeth 30). Each d-axis magnetic path portion 39 is
positioned between two q-axis magnetic path portions 29 in the
circumferential direction. The rotor windings 18n and 18s are disposed in
the slits 44 and are wound around the q-axis magnetic path portions 29
where the magnetic resistance is small. According to the example
configuration illustrated in FIG. 9, the rotating magnetic field that
includes the space harmonics components formed by the stator 12
interlinks with the rotor windings 18n and 18s. Accordingly, DC currents
rectified by the diodes 21n and 21s flow through the rotor windings 18n
and 18s. The q-axis magnetic path portions 29 are magnetized. As a
result, each q-axis magnetic path portion 29 can function as a magnet
where the magnetic pole is fixed (i.e., a magnetic pole portion). In this
case, the induced electromotive forces generated by the space harmonics
on the rotor windings 18n and 18s can be efficiently increased by setting
the width of each q-axis magnetic path portion 29 in the circumferential
direction (i.e., the width G of respective rotor windings 18n and 18s) to
be shorter than the width corresponding to electric angle 180° of
the rotor 14, and further by winding the rotor windings 18n and 18s
around the q-axis magnetic path portions 29 by short-pitch winding.
Further, to maximize the induced electromotive forces generated by the
space harmonics on the rotor windings 18n and 18s, the width θ of
the rotor windings 18n and 18s in the circumferential direction is
preferably set equal to (or substantially equal to) the width
corresponding to an electric angle of 90° of the rotor 14.

[0057]Further, in the present embodiment, permanent magnets 48 can be
disposed on the rotor core 16, for example, as illustrated in FIG. 10.
According to the example configuration illustrated in FIG. 10, a
plurality of magnetic pole portions 49 that can function as magnets where
the magnetic pole is fixed are arranged along the circumferential
direction in a mutually spaced state and are disposed in spaced
confronting relationship with the stator 12 (i.e. the teeth 30). The
rotor windings 18n and 18s are wound around the magnetic pole portions
49. Each permanent magnet 48 is positioned at a portion corresponding to
a position (e.g., midpoint) between two neighboring magnetic pole
portions 49 in the circumferential direction and is disposed in spaced
confronting relationship with the stator 12 (i.e., the teeth 30). The
above-described permanent magnets 48 can be embedded in the rotor core 16
or can be exposed on the surface (outer circumferential surface) of the
rotor core 16. Further, in a case where the permanent magnets 48 are
embedded in the rotor core 16, the permanent magnets 48 can be configured
to form a V-shaped arrangement. According to the example configuration
illustrated in FIG. 10, the rotating magnetic field including the space
harmonics components formed by the stator 12 interlinks with respective
rotor windings 18n and 18s. The DC currents rectified by the diodes 21n
and 21s flow through the rotor windings 18n and 18s, and each magnetic
pole portion 49 is magnetized. As a result, each magnetic pole portion 49
can function as a magnet where the magnetic pole is fixed. In this case,
the induced electromotive forces to be generated by the space harmonics
on the rotor windings 18n and 18s can be efficiently increased by setting
the width of each magnetic pole portion 49 in the circumferential
direction (i.e., the width θ of respective rotor windings 18n and
18s) to be shorter than the width corresponding to electric angle
180° of the rotor 14, and further by winding the rotor windings
18n and 18s around the magnetic pole portions 49 by short-pitch winding.
Further, to maximize the induced electromotive forces to be generated by
the space harmonics on the rotor windings 18n and 18s, the width θ
of the rotor windings 18n and 18s in the circumferential direction is
preferably set equal to (or substantially equal to) the width
corresponding to an electric angle of 90° of the rotor 14.

[0058]Further, in the present embodiment, for example, as illustrated in
FIG. 11, the rotor windings 18n disposed on every other pole in the
circumferential direction can be connected to each other so as to be
electrically connected in series. The rotor windings 18s disposed on
every other pole in the circumferential direction can be connected to
each other so as to be electrically connected in series. More
specifically, the rotor windings 18n wound around the salient poles 19
that can function as magnets having the same magnetic pole (e.g., N-pole)
can be electrically connected to each other as a serial winding. The
rotor windings 18s wound around the salient poles 19 that can function as
magnets having the same magnetic pole (e.g., S-pole) can be electrically
connected to each other as a serial winding. However, the rotor windings
18n and 18s wound around the salient poles 19 that are adjacent to each
other in the circumferential direction (i.e., on which magnets having
mutually different magnetic poles are formed) are electrically isolated
from each other. Two diodes 21n and 21s (i.e., two diodes) are provided
for the rotor windings 18n and 18s that are electrically isolated from
each other. The diode 21n rectifies the current that flows through the
rotor windings 18n that are electrically connected as a serial winding.
The diode 21s rectifies the current that flows through the rotor windings
18s that are electrically connected as a serial winding. In this case, it
is desired to form the magnets having magnetic poles that are mutually
different between the salient poles 19 around which the rotor windings
18n are wound and the salient poles 19 around which the rotor windings
18s are wound (i.e., between the salient poles 19 that are adjacent to
each other in the circumferential direction). To this end, the
current-rectifying directions of the rotor windings 18n and 18s regulated
by the diodes 21n and 21s are set to be opposite each other. According to
the example configuration illustrated in FIG. 11, the total number of the
diodes 21n and 21s can be reduced to only two.

[0059]Further, in the present embodiment, for example, as illustrated in
FIG. 12, the rotor windings 18n and 18s can be wound by toroidal winding.
According to the example configuration illustrated in FIG. 12, the rotor
core 16 includes an annular core portion 17 and salient poles 19 that
project outward from the annular core portion 17 in the radial direction
(i.e., toward the stator 12). Respective rotor windings 18n and 18s are
wound around a predetermined position of the annular core portion 17,
which is close to each salient pole 19, by toroidal winding. According to
the example configuration illustrated in FIG. 12, the rotating magnetic
field that includes the space harmonics components formed by the stator
12 interlinks with the rotor windings 18n and 18s. DC currents rectified
by the diodes 21n and 21s flow through the rotor windings 18n and 18s and
magnetize respective salient poles 19. As a result, the salient poles 19
positioned in the vicinity of the rotor windings 18n can function as
N-poles. The salient poles 19 positioned in the vicinity of the rotor
windings 18s can function as S-poles. In this case, the induced
electromotive forces to be generated by the space harmonics on the rotor
windings 18n and 18s can be efficiently increased by setting the width
θ of each salient pole 19 in the circumferential direction to be
shorter than the width corresponding to an electric angle of 180°
of the rotor 14. Further, to maximize the induced electromotive forces to
be generated by the space harmonics on the rotor windings 18n and 18s,
the width θ of each salient pole 19 in the circumferential
direction is preferably set equal to (or substantially equal to) the
width corresponding to an electric angle of 90° of the rotor 14.
Similar to the example configuration illustrated in FIG. 11, in the
example illustrated in FIG. 12, the rotor windings 18n and 185 that are
adjacent to each other in the circumferential direction are electrically
isolated from each other. The rotor windings 18n disposed on every other
pole in the circumferential direction are electrically connected to form
a serial winding. The rotor windings 18s disposed on every other pole in
the circumferential direction are electrically connected to form a serial
winding. However, even in the example of the rotor windings 18n and 18s
that are wound by toroidal winding, similar to the example configuration
illustrated in FIG. 3, the rotor windings 18n and 18s wound around the
salient poles 19 can be electrically isolated from each other.

[0060]Further, in the present embodiment, for example, as illustrated in
FIG. 13, a common rotor winding 18 can be wound around respective salient
poles 19. According to the example configuration illustrated in FIG. 13,
the rotor winding 18 is short-circuited via a diode 21. Therefore, the
diode 21 rectifies the current so as to flow through the rotor winding 18
in one direction (as DC current). The magnetized directions of the rotor
windings 18 wound around two salient poles 19, which are adjacent to each
other in the circumferential direction, are opposite each other. To this
end, the directions of the winding portions wound around the salient
poles 19, which are adjacent to each other in the circumferential
direction, are opposite each other. Even in the example configuration
illustrated in FIG. 13, the rotating magnetic field that includes the
space harmonics components formed by the stator 12 interlinks with the
rotor winding 18. The DC current rectified by the diode 21 flows through
the rotor winding 18 and magnetizes respective salient poles 19. As a
result, each salient pole 19 can function as a magnet where the magnetic
pole is fixed. In this case, the magnets having mutually different
magnetic poles can be formed by two salient poles 19 that are adjacent to
each other in the circumferential direction. According to the example
configuration illustrated in FIG. 13, the total number of the diode 21
can be reduced to only one.

[0061]However, according to the example configuration illustrated in FIG.
13, magnetic flux variations (tertiary) caused by the space harmonics
components of respective salient poles 19 may be canceled, because the
common rotor winding 18 is used for the salient poles 19 that form the
N-poles and the salient poles 19 that form the S-poles. Therefore, the
torque of the rotor 14 may not effectively increase, as compared with
other example configurations. FIG. 14 illustrates a calculation result of
the amplitude (i.e., variation width) of the flux linkage that interacts
with the rotor windings 18, which can be obtained by changing the
circumferential width θ of the rotor winding 18 wound around each
salient pole 19 in the example configuration illustrated in FIG. 13. In
FIG. 14, the coil width θ is expressed using a value converted into
an electric angle. As illustrated in FIG. 14, the variation width of the
flux linkage that interacts with the rotor winding 18 greatly decreases
if the coil width θ becomes smaller than 90°. Further, the
variation width of the flux linkage that interacts with the rotor winding
18 greatly decreases if the coil width θ becomes greater than
120°. Further, considering the necessity of the coil width θ
that can secure a sufficient cross section for the rotor winding 18, to
further increase the induced current to be caused by the space harmonics
generated by the rotor winding 18 in the example configuration
illustrated in FIG. 13, the width θ of the rotor winding 18 in the
circumferential direction is preferably set larger than the width
corresponding to an electric angle of 90° of the rotor 14 and
further to be smaller than the width corresponding to an electric angle
of 120° of the rotor 14 (i.e., satisfy a relationship
90°<θ<120°). Further, as illustrated in FIG.
14, the amplitude of the flux linkage caused by the space harmonics has a
peak at the coil width θ of 105°. Accordingly, to further
increase the induced current to be caused by the space harmonics
generated by the rotor winding 18 in the example configuration
illustrated in FIG. 13, the width θ of the rotor winding 18 in the
circumferential direction is preferably set equal to (or substantially
equal to) the width corresponding to an electric angle of 105° of
the rotor 14.

[0062]Further, according to the example configuration illustrated in FIG.
15, the rotor winding 18 is wound around each salient pole 19 by wave
winding (i.e., series winding). The magnetized directions of the salient
poles 19, which are adjacent to each other in the circumferential
direction, are opposite each other. To this end, the directions of the
winding portions wound around the salient poles 19, which are adjacent to
each other in the circumferential direction, are opposite each other. In
FIG. 15, a solid line portion of the rotor winding 18 extends along one
side of the salient pole 19 (i.e., the foreside of the drawing), which
corresponds to one end surface side of the salient pole 19 in the
rotational shaft direction. A dotted line portion of the rotor winding 18
extends along the other side of the salient pole 19 (i.e., the backside
of the drawing), which corresponds to the other surface side of the
salient pole 19 in the rotational shaft direction. Further, a portion 18a
indicated by ∘ (white circle mark) with (black circle mark)
positioned therein is a portion where the current flows in a forward
direction relative to the drawing surface. A portion 18b indicated by
∘ (white circle mark) with x (crossing mark) positioned
therein is a portion where the current flows in a backward direction
relative to the drawing surface. Even in the example configuration
illustrated in FIG. 15, the rotating magnetic field that includes the
space harmonics components formed by the stator 12 interlinks with the
rotor winding 18. The DC current rectified by the diode 21 flows through
the rotor winding 18 and magnetizes respective salient poles 19. As a
result, each salient pole 19 can function as a magnet where the magnetic
pole is fixed. In this case, the magnets having mutually different
magnetic poles can be formed by two salient poles 19 that are adjacent to
each other in the circumferential direction. According to the example
configuration illustrated in FIG. 15, the total number of the diode 21
can be reduced to only one.

[0063]In the above-described embodiments, the stator 12 and the rotor 14
are disposed in spaced confronting relationship in the radial direction
that is perpendicular to the rotational shaft 22. However, the rotary
electric machine 10 according to the present embodiment can be configured
as an axial-type rotary electric machine, in which the stator 12 and the
rotor 14 are disposed in spaced confronting relationship in a direction
parallel to the rotational shaft 22 (i.e., in the rotational shaft
direction).

[0064]Although some embodiments for implementing the present invention
have been described, the present invention is not limited to the
above-described embodiments and can be embodied in various manners
without departing from the gist of the present invention.